Monitor circuit for a tabulating card reader



y 1965 T. SAPINO 3,184,582

MONITOR CIRCUIT FOR A TABULATION CARD READER Original Filed March 28, 1958 2 Sheets-Sheet 1 INVENTOR.

RE SAPINO ATTORNEY y 18, 1965 T. SAPINO 3,184,582

MONITOR CIRCUIT FOR A TABULATION CARD READER Original Filed March 28, 1958 2 Sheets-Sheet 2 mvsmox. HEODOyPINO BY mm ATTORNEY United States Patent 0 3,184,582 MONITOR CIRCUIT FOR A TABULATING CARD READER Theodore Sapino, Framingham, Mass, assignor to Honeywell Inc., a corporation of Delaware Original application Mar. 28, 1958, Ser. No. 7261554, now Patent No. 3,081,940, dated Mar. 19, 1963. Divided and this application June 22, 1962, Ser. No. 207,142

5 Claims. (Cl. 235-6111) The present application is a division of an application entitled Improvements in Electrical Monitoring and Control Apparatus bearing Serial Number 724,554, filed March 28, 1958.

A general object of the present invention is to provide a new and improved apparatus for monitoring the opera tion of a tabulating card feeding mechanism. More speciiically, the present invention is concerned with a new and improved apparatus for sensing the presence or absence of tabulating cards in a feed mechanism and also for checking the cards fed through the mechanism to see if they are skewed wherein this apparatus is characterized by its ability to function in a circuit combination with card reading apparatus which incorporates magnetic core storage elements in the associated circuitry.

Tabulating cards of the punched type are widely used in conveying of information in a form in which it may be readily accepted and sensed by electromechanical means. In one such card reading apparatus, it has been found desirable that the punches or holes in the tabulating cards be read directly into suitable bistable magnetic core elements in the course of a normal reading operation. This is conveniently accomplished by utilizing the sensing brush, which is adapted to pass through the holes of the tabulating card, to close an electrical circuit by way of contacting a grounding element on the other side of the card. The closing of this circuit will establish a current flow in a winding which is adapted to set a bistable mag netic core. Once the core has been set, the information may be shifted therefrom into suitable utilization circuits by means well known in the art. In such tabulating card apparatus, it i desirable that a check be made to determine if a card is actually present at a reading station at some particular time during the course of a reading operation. It is further necessary that a check be made to determine if the card is in skew or not. In other words, if the card is not aligned with respect to the reading brushes at the reading station, it is desired that this fact be known by the operator and, if desired, that the card feeding apparatus be stopped. It has been found desirable, in order to minimize the amount of equipment required, that the missing card circuit and/ or the card skew circuits use the normal brush sensing elements at the card reading station, these elements being normally used in the reading of the holes in the card.

In order to effect the desired sensing and monitoring of the cards by the same brushes, a new circuit has been provided, as hereinafter set forth, for utilizing the sensing brushes at predetermined times during each card cycle for sensing and for monitoring. The monitoring circuitry utilized has been devised so that it will not be adversely affected by the presence of a magnetic core circuit which may also be directly connected to the card reading brushes.

It is, therefore, a further more specific object of the present invention to provide a new and improved monitoring circuit for a tabulating card reading apparatus wherein the monitoring circuit may be used directly in conjunction with a magnetic core setting element and magnetic core circuit without the core setting element, the magnetic core circuit, or the monitoring circuit interfering with the operation of the other.

3,184,582 Patented May 18, 1965 It has been found that the present circuit may be used to produce the desired operating features by incorporating a unique combination of timing switches and a transistor circuit which is capable of operating at impedance levels comparable to the impedance levels found in magnetic core circuits without the impedances of either circuit being adversely affected by the other in the course of a normal card reading cycle. In this regard it has been found desirable for a transistor circuit to be provided wherein the transistor of the circuit functions as a switch which is normally biased to be nonconductive in the absence of a condition indicating faulty operation. If a condition should exist at the card reading station indicating that there is a faulty operation, it is desired that the transistor be switched into conduction.

It is, therefore, a further more specific object of the present invention to provide a new and improved monitoring circuit for a card feeding apparatus which incorporates a transistor element normally arranged to be nonconducting and adapted to be biased into a conducting region upon the sensing of a condition at the card feed mechanism indicating faulty operation.

Insofar as monitoring the presence or absence of a card from the reading station at the card feed mechanism, it is necessary that a sensing be made at a predetermined time in each card cycle at a selected hole sensing brush location, preferably a location at the center of the leading edge of the card. In the case of a skew detection circuit, the monitoring circuit is preferably arranged to co-operate with at least two sensing brushes at the reading station where the two brushes are relatively widely separated insofar as reading data from the card is concerned. In this latter case, the monitoring circuit is arranged so that the signals from the two brushes used in the monitoring op eration are buffered together to produce a control signal capable of switching a transistor into a conductive state. The presence of a skew condition is checked during the interval immediately following the time that a tabulating card would normally have left a reading station.

A still further more specific object of the invention is then to provide a new and improved monitoring circuit for a card feeling apparatus which incorporates a transistor switching device normally biased to be nonconductive and which is adapted to be rendered conductive by the presence of a signal from a single reading brush in the case of a missing card circuit, or by a pair of reading brushes in the case of a skew detection circuit.

Another object of the invention is to provide a new and improved coupling circuit for a thyratron control circuit which is adapted to be driven by the control transistor of the present apparatu wherein the coupling circuit will prevent the unwanted firing of the thyratron when power is switched onto the plate circuit thereof.

The foregoing objects and features of novelt which characterize the invention, as well as other objects of the invention, are pointed out with particularity in the claims annexed to and forming a part of the present specification. For a better understanding of the invention, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

Of the drawings:

FIGURE 1 is a schematic representation of a missing card detection and monitoring circuit; and

FIGURE 2 is a schematic showing of a circuit useful in the detecting of the presence of a skew in a card at a card reading station.

Referring to FIGURE 1, there is here illustrated a circuit for sensing the fact that a card may be missing from a card reading station at a time when a reading operation is normally about to take place. This circuit is so arcause a thyratro'n relaycircuit to be. tied: ted. When the card i spresent, the circuit will not ing FIGURE ignore specifically;-thehurneral it} identifies a conducting roller. which is adapted to cooperate with reading brushes for tabulating cards normally used with this apparatus. These cards will pass over the roller 19 and move the cooperating brushes away from tpe rpllcnrc s at are a. .ated tliei'ewitli, unless tlicie areholes in the card. Shown in FIGURE 1 is a single brush 11. Thebrush 11 will normally bealigned with one of the columns on a tabulating card which is adapted to, pass through the reading station. In the present circuit, the brush 11 is adapted to ceasedrer rn asurin tiiepresencc 6i absence acted aiid is preferably a brush located at about the middle of all of the brushes in any time readirig station. Thus, In a card reading station having eighty brushes for an eighty column tabulating card, the brush 11 might well be used for sensing in column 40'.

Associated with the brush 11 is a suitable digital storage element shown as a histablerriagneticcoie 1,2; The core 12 has a winding 13 which is adapted to be conneeted in a closed electrical circuit including a voltage source terminal 14 by way of a resistor 15, brush 11, and the grounded drum iii,

In the normal card reading operation, the presence of L I u hole in a particular column, such as the column 40 wherein the brush 11 is located, will cause a closing of the electrical circuit through the winding 13 and therefore a signal will be Written into the core 12. When a signal is so Written into the core 12, it may then be shifted out 1nto suitable utilization circuitry as is known in the art,

further lead 16 is coupled to the brush 11 and this ead 16 connects the brush to the missing card sensing circuit of the present invention. The lead 16 couples to a cam operated switch 17 and to a diode 13, the latter Of which is connected to the input of a base electrode of a transistor 19, the latter also including suitable emitter and collector electrodes. The operating voltages for the transistor 19 are derived from a plus voltage supply terirnnal 20 which passes by Way of a resistor 21 to a d stribution lead '22. The base of the transistor 19 is biased to be slightly positive by reason of a connection 'to this lead 22. The connecting circuit therefor includes a pair of series connected resistors 23 and 24 with the ase being connected to the junction between the resistors 2 3 and 24,

H A a is supplied for the emitter of the transistor 19 R Way of a further pair of resistors 25 and 26 which are also connected to the supply lead 2-2.

The collector of the transistor 19 is connected to a separate negative voltage supply terminal 27, and a voltdivi'der network including a pair of resistors 28 and 29. The voltage supplies for the transistor 19 are such that the base thereof is biased to be slightly positive with respect to the emitter by approximately one volt. The magnitude of the voltage required is, of course, de-

pendent upon the particular type of transistor which may :be used in the circuit. When the base of this transistor is biased to be slightly positive, the emitter-collector current path will be of relatively high impedance and coneet-i uently substantially no current will be flowing dherein.

"The collector of the transistor 19 is coupled by way of La pair of series connected diodes 30, and a resistor 31 (connected in parallel therewith, to the input circuit of tthe thyratron 32. The input circuit comprises a conr'denser 33 which functions as a filter condenser and a :resistor 34, the latter having a diode 35 connected in I parallel therewith. The thyratron 32 is adapted, when ,triggeredtofire, to supply the necessary current for actiat the sen/i degreepdsiti on in cards per minute.

vating an output indicating l elay he, Ghee the circuit hasfiregitis "i 1 tes s remain iants centimetre state until 'iirneae hperattirfipens a itch 3 7 which is in series .with the plate circuit oftlietliyiatreiri isird di "8 int; be coupled tothelead ld and ar i vghag la claitipthe leadto' a predeter minedvoltagi The-. e'ffect at this is at prevent an h a back voltage from the core 12 from damaging the sensing circuits if the cam switch 17 should be closed.

orisidering,theover-all, operation of the circuit of lfillld 1; edntiide'ratiori is first given to he normal card readirig cycle of the apparatus. By u nitid'ri, and cycle may be considered in terms of degrees with 360 degrees defining a complete card cycle. If the apparatus is operating properly, the normal timing for the leading edge of a cardto arrive. at the reading station will be e cycle. In ano'rmal tabulating .card having holes punches therein, there. is a certain distance from the leading edge before the iiist row on the card Where a punch may appear is reached. Thus, a sensing may be made on this leading edge to deternjiineif in fact the card has arrived at the reading statidn. The sensing is conveniently accomplished at some in the card cycle after 355 /2 degrees and a 9 degree position wild-c the first row of information nor mally reaches the brush.

in the present circuit, the cam 17 is arranged to be operated for a 6 degree interval starting at 359 degrees and continuing until 5 degrees have passed in the card cycle. During that time, the switch 17 will be closed and will be connecting the brush 11 directly to the diode 18 on the input to the base of the transistor 19. If the card is present in the circuit, there will be no al r of the electtical condition existing on the base of the transistor 19 and c'ohsequently the circuit will f m nonc'onducting However, when the switch 17 is closed; and if the card has not reached the brush 11, or is absent from the feed mechanism, the! bfush 11 will engage the surface of the drum 10 and a grour'id circuit will be completed from the base of the transistor 19, through the diode 18, switch 17, lead 16, and brush 11.- The grounding of the base by this circuit is effective to cause the base of the transistor to be negative with respect to the emitter thereof and consequently the transistor will be rendered conducting. When the transistor becomes conducting, the collector thereof will be substantially grounded and this grounding signal will be reflected through the diodes 30 and will cause a voltage to appear on the grid of the thyratron 32 to fire the same. When the thyratron fires, it will cause current to fiow through the relay 36 and the relay will operate its output contacts to provide a suitable indication and/or control function in the card reader circuit.

Once the card has moved beyond the 9 degree position in the card cycle, it will then be sensed in the normal manner by the brush 11 and such other brushes as are in position in the reading apparatus. In any position wherein there is a hole in the card, the current flowing through the brush as the brush engages the drum 10 will be effective to switch the core 12 and write an appropriate signal therein which may be transferred out to a suitable utilization circuit.

It will be apparent from the foregoing circuit that the apparatus is capable of operating to sense the presence or absence of the card at the start of the card cycle without necessitating the disconnection of the brush from the normal reading core circuitry. This is true even though the impedance of the magnetic core circuitry is relatively low. This novel arrangement of circuit elements considerably simplifies the circuitry required in this sensing circuit and greatly enhances the usefulness of the circuit insofar as speed of operation is concerned. In one embodiment of the invention, the cards were fed past the reading station at the rate of approximately 900 Thus, the time to sense for a missing card is less than 1.5 milliseconds, which further points up the need for a circuit having a high speed of response.

It will be noted that the thyratron 32 has a special input circuit provided therefor in the form of the condenser 63, resistor 34, and diode 35. The presence of this circuit is to minimize the effect of spurious voltage signals from the output of the thyratron from affecting the input thereto. In this regard, it should be noted that the closing of switch 37 in the plate circuit will result in a positive signal suddenly appearing at the plate of the thyratron. This positive signal tends to be coupled into the grid circuit by capacitive coupling. The diode 35, in co-operation with the condenser 33, tends to shunt the signal to ground and prevent the control grid from firing the thyratron. Thus, the circuit will be ready to sense the next sensing for a missing card and will not be triggered falsely by any transient signal on the plate thereof.

As each card progresses through the reading mechanism, it will normally leave the reading station at the 229 degree position. If a card is skewed more than a predetermined amount, one end of the card will leave the reading station before the other end does. If the card is skewed more than a predetermined amount, it is desired that the skew be detected and an appropriate signal be generated to inform the operator of this condition and/ or stop the operation of the card feeding mechanism. In one embodiment of the invention, it was found desirable to check for skew at the 237 degree position of the card cycle. Thus, at the time of sensing, if any part of the card remains under reading brushes located near the ends of the card, then it is desired that a signal be generated indicating a skew condition.

The .circuitry of FIGURE 2 is the circuitry .used for detecting the presence of skew. As in the case of FIG- URE l, the brushes used for sensing the skew are also used in the normal reading of the card. Referring specifically t-o FIGURE 2, there are shown co-operating with the reading station drum a pair of brushes and 51. In the case of an eighty column card, the brushes which may be used for the skew detection should preferably be located near the ends of the cards. Thus, the brush 51 may well be the second brush associated with the second column of the card while the brush 50 may be the seventy-ninth brush associated with the seventyninth column on the card. Connected in circuit with the brush 51 is a suitable magnetic core element 52 having a control set winding 53 wound thereon. Connected in circuit with the brush 50 is a further core 54 having a winding 55 thereon.

The brush 50 is coupled by way of the diode S6 to an R.C. integrating circuit including resistor 57 and a condenser 58. This integrating circuit is coupled to a diode 59 which functions as a buffer diode in the present circuit. The brush 50 is clamped to a positive voltage by way of a clamping diode 60.

The brush 51 is coupled by way of a coupling diode 61 to a further integrating network comprising a resistor 62 and a condenser 63. The output of this integrating network is connected to a buffer diode 64. The buffer diodes 59 and 64 are in turn coupled to an output lead 65 which passes through a timing cam switch 66. A further clamp diode 60A is connected to the brush 5-1. The cam time switch 66 is adapted to be activated at the 237 degree position and will remain activated for a predetermined number of degrees thereafter and will open \before the time that the next card would normally arrive at the sensing stations. The timing cam 66 is coupled by way of resistor 67 to the emitter of a transistor 68.

The transistor 68, in addition to the emitter, includes the normal base and collector electrodes. The transistor 68 is connected in the common base configuration with the base thereof being connected to ground by way of a resistor 69 having a condenser 70 in parallel therewith. The collector is connected to a minus voltage supply by way of a voltage divider network including a resistor 72 and a resistor 73. The base of the transistor is connected to a positive voltage source which includes a resistor 74 and leads to a plus voltage terminal 75 by way of a filter resistor 7 6. The voltage terminal 75 also supplies voltage to the buffer circuit by way of a pair of resistors 77 and 78 and a further diode 79, the latter of which is connected to the output lead 65 of the buffer circuit. A biasing voltage is also supplied by way of the plus supply terminal 75 and resistors 86 and 81, which are connected to the anodes of the diode 61 and 56, respectively, on the input to the buffer circuit.

The output collector electrode of the transistor 68 is coupled in a manner similar to that of FIGURE 1 to a thyratron 85, the latter of which is adapted, when fired, to activate an appropriate relay 86 in the output circuit thereof.

In considering the operation of the circuit as disclosed in FIGURE 2, it should be kept in mind that in the normal reading operation, the brushes 50 and 51 will be functioning to sense holes in the cards as they pass over the drum 16. Thus, the presence of a hole in the cards will permit the closing of an electrical circuit for setting the associated cores.

As pointed out above, when the card has passed the reading station, it will normally have passed out from under the reading brushes at the 229 degree position of the card reading cycle. If the card is in skew such that a part of the card remains under one or the other of the brushes 50 and 51 at the 237 degree position of the card cycle, the closing of the switch 66 will be elfective to cause a signal to appear on the emitter of the transistor 68. Thus, if the brush 50 should not be grounded due to the presence of a card between the brush and the drum 10 and the switch 66 closes, a signal will be applied from the plus voltage terminal 75 to the integrating network formed by the resistor 57 and condenser 58. The plus voltage will be effective to cause the diode 59 to conduct in the buffer circuit and therefore to couple a positive signal into the emitter of the transistor 68. With this positive signal on the emitter, and with the base effectively connected to ground, the transistor 68 will be rendered conducting in the emitter-collector path. This will cause the potential of the collector to approach ground potential and consequently the thyratron will fire. The thyratron 85 will remain conducting, once it has fired, until such time as an operator opens the circuit in series with the plate thereof.

If the skew should be in the opposite direction such that the brush 51 has a card thereunder at the time that the timing cam 66 closes, the circuit will again function to cause the conduction of the transistor 68 through the other buffer diode 64 and thus the thyratron 85 will again be fired.

If the card is passing through the circuit in a normal manner, both of the brushes 50 and 51 will be engaging the drum 10. This will cause the grounding of the cathodes of the diodes 56 and 61 and consequently the grounding of the input leads to the integrating circuits formed by the R.C. networks on the input of the buffer diodes. This will mean that the voltage condition on these diodes and thus on the emitter of the transistor 68 will not be materially disturbed so that the transistor 68 will remain nonconducting.

It will be noted that in this particular skew detection circuit, the brushes 50 and 51, even though they are con nected in circuit with magnetic core storage circuits, may nevertheless be used directly for sensing card skew. As with the missing card sensing circuit, this feature considerably enhances the use to which the circuit may be put and the speed with which it may be operated.

While, in accordance with the provisions of the statutes, there has been illustrated and described the best forms of the invention known, it will be apparent to those skilled in the art that changes may be made in the apparaan e ases I? tus described Without departing froiri spirit of the in vention as set forth in the appended claims arid that some cases certain features of the invention may be used to advantage without a corresponding use of other feat'l H' S.

Having now described the invention, What is claimed as new iieiv'el and for which it is desired to secure Letters Patent isf 1. A monitor circuit for a tabulating' card reader compriisiiigia pair of hole sensing brushes adapted to engage a grounded surface in the absence of a tabulating card or upon the presence of holes in a tabulating card, a bistable magnetic core circuitdirectly connectedto said brushes and each adapted to have a core therein set by the presember it grounding signal at the related one oi said brushes, a transistor circuit having an emitter-collector circuit, bia's means connected to said transistor to maintain' said transistor effectively nonconducting in said emitter-collector circuit, at'iming switch synchronously operated in connection with the sensing of tabulating cards, at seciond bias circuit, and means including said timing switch and one or the other of said brushes for effectively activating said second bias circuit on said transistor to render said transistor conducting in said emitter-collector circuit upon the presence of a predetermined conducting condition at one or the other of said brushes.

2. A monitor circuit for a tabulating card reader comprising a pair of hole sensing brushes adapted to engage a grounded surface in the absence of a tabulating card or upon the presence of a hole in a tabulating card, a bistable magnetic core circuit comprising magnetic cores having windings directly connected to said brushes and adapted to be set by the presence of a grounding signal at said brushes, a butter circuit having a pair of inputs connected to said brushes, a transistor circuit having an emitter-collector circuit, bias means connected to said transistor to maintain said transistor effectively nonconducting in said emitter-collector circuit, a timing switch synchronously operated in connection with the sensing of tabulating cards, and means including said timing switch connecting the output of said butter to said transistor to render said transistor conducting in said emitter-collector circuit upon the presence of a predetermined electrical conducting condition at said brushes.

3" A r'nonitor circuit as defined in claim 2 wherein said pair of buffer inputs include a signal integrating circuit.

{1.- In a monitor circuit for checking the skew of a tabulatiiig card passing through a card reading apparatus, the combination comprising a pair of card sensing brushes positioned to engage a tabulating card at displaced points, a magnetic core storage circuit coupled to each of said brushes, a conducting surface adapted to be engaged by said brushes in the absence of a card, a diode coupling circuit connected to each of said brushes and adapted to be connected to a butter circuit having a pair of inputs and a single output, a transistor having an emitter-collector circuit, said transistor normally being biased to be nonconductive in the emitter-collector circuit, a switch adapted to be closed at a time when a tabulating card is normally not present under said brushes, and means including said switch connecting said butter output to said transistor to bias said transistor to be conductive in said emitter-collector circuit when either or both of said brushes is not engaging said conducting surface.

5. In a monitor circuit for checking the skew of a tabulating card passing through a card reading apparatus, the combination comprising a pair of card sensing brushes positioned to engage a tabulating card at displaced points, a magnetic core storage circuit coupled to each of said brushes, a conducting surface adapted to be engaged by said brushes in the absence of a card, a diode coupling circuit connected to each of said brushes and adapted to be connected to a butter circuit having a pair of inputs and a single output, a transistor having an emitter-collector circuit, said transistor normally being biased to be nonconductive in the emitter-collector circuit, a switch adapted to be closed at a time when a tabulating card will normally not be present under said brushes, means including said switch connecting said butter output to the emitter of said transistor to bias said transistor to be conductive in said emitter-collector circuit when either or both of said brushes is engaging said conducting surface, and an indicating means connected to said transistor to sense the presence or absence of conduction in said emitter-collector circuit.

No reference cited.

MALCOLM A. MORRISON, Primary Examiner. 

1. A MONITOR CIRCUIT FOR A TABULATING CARD READER COMPRISING A PAIR OF HOLE SENSING BRUSHES ADAPTED TO ENGAGE A GROUNDRED SURFACE IN THE ABSENCE OF A TABULATING CARD OR UPON THE PRESENCE OF HOLES IN A TABULATING CARD, A BISTABLE MAGNETIC CORE CIRCUIT DIRECTLY CONNECTED TO SAID BRUSHES AND EACH ADAPTED TO HAVE A CORE THEREIN SET BY THE PRESENCE OF A GROUNDING SIGNAL AT THE RELATED ONE OF SAID BRUSHES, A TRANSISTOR CIRCUIT HAVING AN EMITTER-COLLECTOR CIRCUIT, BIAS MEANS CONNECTED TO SAID TRANSISTOR TO MAINTAIN SAID TRANSISTOR EFFECTIVELY NONCONDUCTING IN SAID EMITTER-COLLECTOR CIRCUIT, A TIMING SWITCH SYNCHRONOUSLY OPERATED IN CONNECTION WITH THE SENSING OF TABULATING CARDS, 